1. Technical Field
The present invention relates to a recording apparatus and a medium feeding device which include a medium accommodation unit for accommodating a medium and a medium detection unit that detects the presence or absence of the medium in the medium accommodation unit.
2. Related Art
In a recording apparatus represented by a facsimile machine and a printer, a sheet feeding tray (cassette) which is attachable to and detachable from an apparatus body has been widely used in the related art. In some cases, a sensor is disposed so as to detect the presence or absence of a sheet or to detect the presence or absence of the sheet feeding cassette itself. In addition, when separate sensors respectively detect the presence or absence of the sheet and mounting of the sheet feeding cassette, the cost is increased. In view of the increasing cost, a sheet feeding device disclosed in JP-A-2006-282311 has a configuration where one sensor detects the mounting of the sheet feeding cassette and the presence or absence of the sheet.
Incidentally, the number of sheets inside the sheet feeding tray varies each time. Accordingly, for example, in a configuration where an optical sensor is arranged at a position opposing the sheet feeding tray and the presence or absence of the sheet is detected by using a change in reflectivity, there is a possibility that detection accuracy may also vary due to a changing distance between the optical sensor and the sheet depending on the number of sheets.
For example, when the number of sheets is small, a reflection position (uppermost position of the sheet) of light emitted from the optical sensor is far from the optical sensor. Accordingly, there is a possibility that a light amount of reflection light received by a light receiving unit may be decreased and thus the detection accuracy may be degraded. In order to prevent such a problem, the light amount of the reflection light is determined based on a case where the number of sheets is small. In this case, there is a possibility that the light amount of the reflection light received by the light receiving unit may be increased when the number of sheets is large and the light receiving unit may be progressively degraded.